Epihalohydrin cure regulators

ABSTRACT

A process for controlling premature curing of epihalohydrin polymers comprising heating an epihalohydrin homopolymer or a copolymer of epihalohydrin with a compound selected from the group consisting of imidazolidones, phthalimides and hydantoins.

O Unlted States Patent 1191 1111 3,898,202 Fath Aug. 5, 1975 [54] EPIHALOHYDRIN CURE REGULATORS 3,473,667 10/1969 Corun et al. 260/309.7 3,513,139 5/1970 Corun et al. 260/795 [75] Inventor: 'Q Fat, Cuyahoga Falls 3.546.185 12/1970 Corzm ct al. 260/795 Ohm 3,562,225 2/1971 Corzm et a1. 260/79.5 3,586.696 6/1971 Kerwood et al. 260/326 [73] Asslgnee' z f f TlreosfilRubber 3.640.976 2/1972 Boustany 260/795 8 l 3.717.592 2/1973 Rave 260/2 A [22] Filed: Nov. 5, 1973 [211 App]. NO; 413,127 Primary Examiner-Melvin Goldstein Assistant Examine/-13. A. Nielsen Atturnqv, Agent, or FirmF. W. Brunner; Cv R. U-S. n n A Schupaach; Wallace Jr [51] Int. Cl? C08G 65/32; C08J 3/24 [58] Field of Search 260/2 A, 79 R, 79.5 R

[57] ABSTRACT References Cited A process for controlling premature curing of epihalo- UNITED STATES PATENTS hydrin polymers comprising heating an epihzllohydrin 3,007,902 11/1961 Nelson 260/79 homopolymer or a copolymer of epihalohydri" with 3,057,832 10/1962 Brock 260/79 Compound Selected from the group Consisting of 3,l77.l82 4/1965 Cottle et al. 260/79.5 m zolid n s, phthalimides and hydantoins. 3,341,491 9/1967 Robinson 260/45.75 3,427.319 2/1969 Coran et al, 260/3092 6 Clalms N0 Drawmgs EPIHALOHYDRIN CURE REGULATORS This invention relates to a process for cure regulation of epihalohydrin polymers including homopolymers and copolymers.

The polymers based on epihalohydrins are saturated, high molecular weight, aliphatic polyethers having halomethyl sidechains. The halogen most commonly used is chlorine, although bromine is also known. The copolymer form generally utilizes ethylene oxide in the copolymerization. Epihalohydrins can be cured with materials that react difunctionally with the halomethyl sidechains. Representative examples of such curing materials are diamines, ureas, thioureas and ammonium salts.

A problem commonly encountered during the processing of epihalohydrin rubbers is scorch. Scorch is defined as the premature curing of the polymer. Scorch is undesirable because it prevents or interferes with further processing. It is therefore desirable that rubber additives be used which reduce scorching. Such compounds are commonly referred to as cure regulators or retarders.

The process of this invention comprises mixing a combination of the epihalohydrin polymer and a curing material described above with from about 0.5 part to about 7.0 parts by weight per 100 parts by weight based on the polymer, preferably from about 1.5 to about 4.5 parts by weight per 100 parts by weight based on the polymer, of an organic material selected from imidazolidones, phthalimides and hydantoins and curing the resulting composition by heating. The materials used as cure regulators are selected from the group consisting of (I) imidazolidones structural (11) phthalimides having general II C 3 0 N s-N and (111) hydantoins.

1n the above formula R and R are the same or different radicals selected from the group consisting of hydrogen, alkyl radicals having from 1 to 8 carbon atoms, cycloalkyl radicals having from 5 to 8 carbon atoms, piperidine and morpholine.

Representative examples of alkyl groups in the above formulas are ethyl, methyl, isopropyl and n-butyl. Examples of cycloalkyl radicals are cyclohexyl, cycloheptyl and cyclooctyl.

The cure regulators can be compounded or mixed with the polymer using internal mixers such as Banbury mixers or by mill mixing. vulcanization is achieved by heating the resulting mixture at a temperature in the range of from about 120 C. to about 260 C. Generally a temperature in the range from about 130 C. to about 200 C. is .used. Curing time will vary from about one minute to about 240 minutes. Usually the time required for curing is from about 10 minutes to about 60 minutes.

Representative examples of cure regulators of the present invention are given by group below.

GROUP 1 IMIDAZOLIDONES ,3 bis(diisopropylaminothio)-2-imidazolidone ,3 bis(piperidinothio)-2-imidazolidone ,3 bis(di-n-butylaminothio)-2-imidazolidonc 3 bis(morpholinothio)-2-imidazolidone GROUP 11 PHTHALIMIDES N-(dicyclohexylaminothio) phthalimide N-(diisopropylaminothio) phthalimide N-(piperidinothio) phthalimide N-(morpholinothio) phthalimide GROUP 111 HYDANTOINS 1,3 bis(morpholinothio)-5,5-dimethyl hydantoin 1,3 bis(dibutyl)-5,S-dimethyl hydantoin In addition to the cure regulating agents, the polymer composition can contain other compounding materials such as additives and reinforcing materials which are normally used with vulcanized rubber products. Representative examples of such additives are metal oxides, reinforcing agents, pigments, fillers, softening agents, antioxidants, plasticizing agents, etc. The oxides of the Group 11 metals of the Periodic Table increase the degree of cure in a given vulcanization time, and the vulcanized products have a light color valuable in certain uses. Representative examples of such metal oxides are zinc oxide, and cadmium oxide.

The invention is described in the working examples given below in which parts and percentages are by weight unless otherwise indicated.

In experiments (l-13) mixing was effected with a two-paddle, water cooled, size B laboratory Banbury. All experimental compounds were mixed using the following procedure. The Banbury was charged with epichlorohydrin polymer, carbon black, stabilizers, process aids and plasticizers. The ram was lowered and the batch was mixed 3 /2 minutes at 50 revolutions per minute (rpm) rotor speed. At 3 /2 minutes the ram was raised and the Banbury throat was swept down. The ram was then lowered and the batch was mixed for an additional two minutes. The batch was discharged at a temperature between C. and C. The batch is sheeted out on a two roll mill to a gauge of 0.075 inch and allowed to rest for between 24 and 48 hours.

The curing agents and cure regulators were added on a two roll mill. The compound was sheeted to approximately 0.020 inch with the mill roll temperature at approximately 100 C. Ethylene thiourea and cure regulators were added. The batch was cross cut five times, rolled off the mill and passed endwise through the mill bite three times. The batch was then sheeted off the mill rolls at 0.050 gauge and allowed to rest for between 24 and 48 hours before curing at C.

The curing characteristics were determined at 160 C. with an oscillating disc rheometer (manufactured by Monsanto). The rheometer recorded the torque exerted on the 3.8 cm. diameter rotor which oscillated 100 times per minute and oscillated with an angle of 5 over a predetermined duration of time.

Curing characteristics as measured with the oscillating'disc rhe ometer described above were measured as to carbon black blends comprising epichlorohydrinll phthalic anhydride 1 l2 N-nitroso diphenylamine l3 N-cyclohexylthio phthalimide ethylene oxide copolymer (Hydrin 200 produced by Tablet Goodrich Chemicals Company). The formulation is 5 shown in Table'l below. The carbon black used was Parts FEF type. D octyl phthalate, sorbitan monostearate, dibasic lead phthalate, dibasic lead phosphite and eth- Hydrin 200 100.0 ylene thiourea curative were used as the balance of the black (FEF) Dioctyl phthalate 5.0 system. The compounds of this invention were added 10 Sorbimn moms-{came 21 and compared to prior art compounds as described be- Dibasic le p k l C d 1 th h 8 h f Dibasic lead phosphite 5.0 ow. ompou n s roug aret ccompoun so t is Ethylencthioumu L invention while compounds 9 through 13 are the prior Experimental rctardcr (1.25 X moles art compounds.

In Tables 1 through [V below, the experimental compounds are identified using thefollowing designations:

0 none 1 1,3-bis(morpholinothio)-2-imidazo1idone 2 l,3-bis(diisopropylaminothio)-2-imidazolidone The blended imidazolidones and their respective 1 quantities are shown in Table 11. The data in Table 11 shows that vulca'nizing systems of this invention exhibit sufficiently long induction periods and achieve high degrees of vulcanization. Cure times for compositions containing the various materials were established by 3 l,3-bis(piperidinothio)-2-imidazolidone 4 1,3bis(di-n-butylaminothio)-2-imidazolidone the crosslinked density (T values in minutes as deter- 5 N-(dicyclohexylaminothio)-phthalimide mined by the Monsanto Rheometer previously de- 6 N-(diisopropylaminothio)-phtha1imide scribed.

Table 11 g Mooney Scorch at 270 F. (132 c.) 1

Min 44 9 37 38 34 43 44 T 2.7 11.5 9.4 11.0 10.5 5.3 6.1 Rheometer at 320 F. (160 C.) I V Max. 91 84 86 91 85 79 80 VMin. 19 15 14 15 14 16 1'6 TAZ 3.2 5.0 3.9 5.1 4.8 3.6 4.0 T 93 45 42 47 40 55 '5 Stress-Strain Properties (Cure T at 160 C.)

Tensi1e(Mn/M 11.1 13.2 12.6 15.2 11.3 12.5 13.2

, 7n Elongation 230 360 320 310 290 335 320 100% Modulus 5.9 4.5 4.8 5.6 4.4 4.4 4.5 Shore A Hard. 72 71 71 66 69 70 68 f 40 7 N- (piperidmothio)-phthalimide Table 111 below shows the effect of phthalimides 8 l,3-bis(morph01inothio)-5,S-dimethylhydantoin much as Table 11 shows the result of imidaz'olidones.

' 1 Table 111 o 5 6 7 10 ll Mooney Scorch at 270 F. Min 44 40 39 39 44 50 1' Rheometer at 320 F.

' V Max. 91 90 90 88 87 v Min. 19 16 15 15 16 19 TA2 3.2 3.4 3.2 3.6 3.7 2.6 T 50 48 48 45 50 50 Stress-Strain (Cure T at 160 C.) Tensile(Mn/M 11.1 12.7 12.5 13.6 11.5 12.0 Elongation 230 275 270 300 2 50 265 Modulus 5.9 5.5 5.3 5.3 -5.5 5.3 Shore Hard. 72 73 69 70 73 73 9's'a1ic'yc1ic 'acid' Table 1V shows the effect of hydantoin as compared l0benzoic acid 60 to the prior art compounds.

Table IV ,Mooney Scorch at 270 F. I

Min 44 39 50 .44 50 43 44 V Table IV -Continued Rheometer at 320 F.

V Max. 91 80 92 88 87 79 80 V Min. 19 l4 l9 l6 l9 l6, l6

T 5O 50 50 50 5O 55 55 Stress-Strain (Cure T at 160 C.) TenSile(Mn/M 11.1 13.6 11.8 11.5 12.0 12.5 13.2 Elongation 230 370 230 250 265 335 320 100% Modulus 5.9 4.5 6.0 5.5 5.3 4.4 4.5 Shore A Hard. 72 70 73 73 73 70 68 The above data demonstrate that the regulating 1 claim:

agents of this invention are capable of providing a long i l. A process for the curing of an epihalohydrin polyinduction period and achieving a high degree of vulcamer selected from the group consisting of (A) epihalonization. This allows more effective use of this polymer hydrin homopolymers and (B) epihalohydrin ethylene in applications requiring long induction periods. oxide comprising mixing a combination of the epihalo- The imidazolidone materials all improve scorch behydrin homopolymer or copolymer and curing agents havior, shorten cure time and improve tensile which reacts difunctionally with the halo methyl side strengths. Scorch control effectiveness at equal molar chains while in the presence of from about 0.5 to about levels of substituted imidazolidones is: mor- 7.0 parts by weight per 100 parts by weight based on pholino piperidino dibutyl diisopropyl control. the polymer of an organic material and heating the mix- Phthalimides also increased initial tensile and elongature at a temperature of from about 130 C. to about tion properties. However, relative to imidazolidones, 200 C. for a time sufficient for curing to take place scorch was impaired. Phthalimide scorch control is in wherein the organic material is a phthalimide having the order: piperidino dicyclohexyl diisopropyl conthe general structural f l trol.

The hydantoins produce a high state of cure as well 0 as impart excellent scorch protection. j

The polymer compositions prepared by curing using f i a the compounds of this invention can be used in prod- N \DJT ucts such as tires, molded goods and industrial rubber ,1 products such as transmission belts and hose, especially 1i high temperature hose which must contain flexibility. 0

Table V Cure Regulators in Hydrin 100 and Hydrin 200 Rank .as

Scorch Time Max. Rheometer Scorch at 270 F. Torque During Inhibitor (Min.) Cure (in. lb.)

Material 100 200 100 200 100 200 1,3-bis(morpholinothio)-2-imidazolidone 1 1 1 1.0 l 1.5 79 84 l,3-bis(piperidinothio )-2-imidazolidone 2 r 2 10.6 1 1.0 92 91 l,3-bis( dibutylaminothio )-2-imidazolidone 3 3 9.7 10.5 88 85 1,3-bis( diisopropylaminothio )-2-imidazolidone 4 5 8.8 9.4 87 86 l,3-bis( morpholinothio )-5,5-dimethylhydantoin 5 4 8.7 10.0 80 80 N-nitroso diphenylamine 6 10 7.0 5.3 72 79 N-cyclohexylthiophthalimide (PVl) 7 7 6.2 6.1 75 8O N-(dicyclohexylaminothio)-phthalimide 8 8 6.0 5.9 91 90 N-(piperidinothio)-phthalimide 9 6 5.6 6.6 97 90 N-( diisopropylaminothio )-phthalimide l0 9 5.5 5.5 93 90 phthalic anhydride 1] 13 4.4 3.5 83 87 control nothing added 12 14 4.3 2.7 84 91 salicyclic acid 13 12 4.1 3.4 81 92 benzoic acid 14 11 3.8 3.7 79 88 As Table V shows, prior art regulators either reduce wherein R and R are the same or different radicals sethe state of cure (numbers 6 and 7) or have little effect on scorch (numbers 11, 13 and 14) and are therefore not desirable. In contrast, materials of this invention improve scorch delay with a minimal loss in state of cure. Examination of the data from numbers 2, 8, 9 and 10 indicates even a higher state of cure and excellent scorch delay in ethylene thiourea cured polymers containing no sulfur.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the spirit or the scope of the invention.

and ethylene oxide.

5. A process described in claim 1 wherein the or ganic material is present from [.5 to 4.5 parts by weight per 100 parts by weight of the polymer.

group consisting of zinc oxide andcudmium oxide. 

1. A PROCESS FOR THE CURING OF AN EPHALOHYDRIN POLYMER SELECTED FROM THE GROUP CONSISTING OF (A) EPIHALOHYDRIN HOMOPOLYMERS AD (B) EPIHALOHYDRIN ETHYLENE OXIDE COMPRISING MIXING A COMBINATION OF THE EPIHALOHYDRIN HOMOPOLYMER WITH COOLYMER AND CURING AGENTS WHICH REACTS DIFUNCTIONALLY WITH THE HALO METHYL SIDE CHAINS WHILE IN THE PRESENCE OF FROM ABOUT 0.5 TO ABOUT 7.0 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT BASED ON THE POLYMER OF AN ORGANIC MATERIAL AND HEATING THE MIXTURE AT A TEMPERATURE OF FROM ABOUT 130*. TO ABOUT 200* C, FOR A TIME SUFFICENT FOR CURING TO TAKE PLACE WHEREIN THE ORGANIC MATERIAL IS A PHTHALIMIDE HAVING THE GENERAL STRUCTURAL FORMULA
 2. A process as described in claim 1 wherein the phthalimides are selected from the group consisting of N-(dicyclohexylaminothio)-phthalimide; N-(diisopropylaminothio)-phthalimide; N-(piperidinothio)-phthalimide; and N-(morpholinothio)-phthalimide.
 3. A process as described in claim 1 wherein the epihalohydrin polymer is an epichlorohydrin homopolymer.
 4. A process as described in claim 1 wherein the epihalohydrin polymer is a copolymer of epichlorohydrin and ethylene oxide.
 5. A process as described in claim 1 wherein the organic material is present from 1.5 to 4.5 parts by weight per 100 parts by weight of the polymer.
 6. A process as described in claim 1 wherein the cure regulators are used with metal oxides selected from the group consisting of zinc oxide and cadmium oxide. 